Conventionally, various types of sewing machines have been suggested that are provided with a feed dog lowering mechanism that lowers the feed dog below the needle plate to render the feed dog inoperable to execute cloth feed. Also, sewing machines have been suggested in which the feed dog lowering mechanism operates in synchronism with the presser foot lifting lever.
For example, the sewing machine described in JP S63-46711 A (hereinafter referred to as patent document 1), includes a feed dog lowering unit configured by a vertical feed arm; a vertical feed plate; and an engagement pin allowing disconnection of a connection between the vertical feed arm and the vertical feed plate and an engagement head of the engagement pin. In such sewing machine, operation of the presser foot lifting lever to lift the cloth presser moves a plurality of levers in synchronization therewith to consequently separate the engagement head of the engagement pin from an engagement hole of the vertical feed plate, thereby resulting in the lowering of the feed dog.
In the sewing machine described in patent document 1, the engagement head of the engagement pin is separated from the engagement hole of the vertical feed plate. At this time, the feed dog and the feed base to which the feed dog is secured is rapidly moved in synchronization with the operation of the presser foot lifting lever to lift the cloth presser, consequently causing an unpleasant rattling noise.
Moreover, the feed dog becomes switched to the lowered position every time the presser foot lifting lever is operated to lift the cloth presser regardless of whether the sewing operation is ongoing or completed. Since the rattling noise occurs on a consistent basis upon such operation of the presser foot lifting lever, the user may consider the noise indicative of a machine failure.